Chair Backrest

ABSTRACT

A chair backrest comprises a closed loop frame, a net, a frame cover, and the subsidiary supporting-arms. The frame includes a protruding loop edge, defining a global frame-net interface with frame fixing holes therein. A loop-like net fixing piece is used for nailing the border of the net onto the frame-net interface. The subsidiary supporting-arms consists of a pair of branching poles; the ends of the branching poles are connected to a common base with the upper portion of the poles fixed to the frame by frame-arm fixing devices and frame-arm fixing pieces. A back reinforcement board traversing between the right side and the left side of the frame can be added to the rear side of the frame to further support the frame against forces applied.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chair backrest. In particular, itrelates to a backrest with a net which provides stronger support againstforces applied, and an enhanced stability in frame-net assembly, alongwith significant ventilation, sustained elasticity, and substantialdurability of the net.

2. Background Art

A disadvantage of conventional backrests made with an outer surface ofcloth or leather is the lack of ventilation, resulting in a sweatysituation for a chair occupant after sitting on for some time. Someimproved conventional backrests are equipped with a ventilated soft net,and a loop frame made of hard plastics. The ventilating net is theninstalled in its associated loop frame by connecting pieces (such as ametal plate) along the edge or end portions of the net, the disadvantageof which includes:

(1) When forces applied by a user's back to the soft net of the backrestare substantially large, connecting pieces engaging the frame with thenet is very likely to be displaced out of its original position,resulting in dislocation of the net and thereby dissociation of the netand the frame.

(2) Due to the sensitivity of hard plastic materials to environmentaltemperatures, the shape of a backrest frame made of hard plastics tendsto deform with the temperatures; the frame has a tendency to contract inlow temperatures, and to expand in high temperatures, adverselyeffecting the durability of the frame.

(3) The supporting force of a conventional chair backrest relies mostlyon a single frame of hard plastics, which is not structurally durablefor an overweight chair occupant.

SUMMARY OF THE INVENTION

It is the therefore purpose of this invention to provide acost-effective compact chair backrest which is easy to assembly, andyet, offer substantially ventilation, sustained elasticity, and longerlife of the chair net. What distinguishes the present invention from theprior arts includes:

-   (I) The unique configuration of the frame-net interface, which    includes a huge global outer surface area of the frame, rather than    just some localized spots along the border of a net; the former does    a better job in securing the net onto the frame than the latter.    Such a global frame-net interface is created by having a protruding    eaves along the loop-like frame. The cross-sections of the frame-net    interface thus designed may have a shape similar to a mirror image    of L (such as “┘”), an upside-down L (such as “Γ”), or an    upside-down and mirrored image of L (such as “┐”), depending on    different sections of the frame concerned (when a partially front    side view is taken). In sum, the frame-net interface contains two    planes forming a sharp angle close to 90-degree, which intensifies    the elastic tension of the net, and at the same time, increases the    frame-net contact area without degrading the outer appearance of the    backrest.-   (II) In a similar way, the net fixing device in the present    invention is embodied by a global fixing loop lying on top of the    net over the frame-net interface, in addition to the conventional    fasteners and fixing bores.-   (III) A loop-like frame cover, mounting on top of the frame-net    interfacing area, acts as an extra force (beside the net fixing    loop, and the conventional fasteners and fixing holes) to stabilize    both the net and the net fixing loop underneath; in the meantime, a    suppressing lock jutting out along the inner surface of the frame    cover is used to further stabilize the border of the net and the net    fixing loop in position.-   (IV) The unique configuration of supporting arms intensifies the    frame against deformation caused by constant or extreme temperature    changes, or over-weights of a chair occupant.-   (V) A back reinforcement board, attached to the rear of the frame on    each of the right and left side of the frame, gives further support    for the loop-like frame structure.

Having examining the differences between the present invention and theprior arts, we will now summarize the prevent invention as follows.

This invention features a backrest with four main components: (1) aloop-like frame made of hard plastics, (2) an elastic latticed net, (3)a frame cover, and (4) a pair of frame supporting arms.

A preferred embodiment in this invention has a net locked in closelywith an ergonomically configured frame, armored with a curved-V shapesupporting-arms, and a back-reinforcement board traversing the right andleft side of the frame to prevent the frame from being deformed orruptured. Furthermore, to prevent the net from coming off the framewhich it is originally engaged to, a fixing loop and a frame cover areused to secure the border of the net onto the frame.

To be more specific, the outer front-most periphery of the frame (facingtoward a chair occupant's back) protrudes out of the frame, togetherwith the opposing outer back-most periphery of the frame, defining aloop-like frame-net contact area, which has a sharp angle. The border ofthe net is secured onto the frame-net contact area by a fixing loopplaced on its top. A frame cover, configured in a way to fit onto theframe, is installed over the frame-net interface, hemming in (within itsinner confine) both the net border and the net fixing loop underneath.

The advantages of the present invention over the known prior art willbecome more apparent to those of ordinary skilled in the art uponreading the following descriptions in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective front view of a chair backrest inaccordance with the present invention.

FIG. 2 is an exploded perspective rear view of a chair backrest inaccordance with the present invention.

FIG. 3 is a perspective front view of the frame and the latticed net inassembly, with a net fixing loop (shown in darkened dashed line)mounting on top of the net.

FIG. 4 is a perspective assembly front view of a chair backrest inaccordance with the present invention.

FIG. 5 is a perspective assembly rear view of a chair backrest inaccordance with the present invention.

FIG. 6 is a side cross-sectional assembly view of a chair backrest inaccordance with the present invention, with two partially enlargedviews.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1-2, a backrest in accordance with the presentinvention generally comprises a frame 1, a latticed net 2, a frame cover3, and supporting arms 4.

The frame 1 is made from hard plastics in the shape of a loop tiltingoutwardly in the lower back portion thereof. At the rear side of theframe 1 (facing away from a chair occupant) is equipped with aback-reinforcement board 11, traversing between the left and the rightside of the frame 1. The back-reinforcement board curves toward the rearof the frame and comprises ventilating bores 111. The frame 1 is furtherintensified by the back reinforcement board 11. As a result, the elastictension of the net 2 installed over the frame 1 is also enhanced.

The loop-like front edge 12 of the frame 1 protrudes outwards (facing achair occupant) and defines a frame-net interface 13, the shape of whichat any point of the frame has a sharp angle like a mirror image of L(such as “┘”), an upside-down L (such as “Γ”), or an upside-down andmirrored image of L (such as “┐”), depending on different sections ofthe frame concerned. The loop-like front edge 12 curves smoothly at thetwo upper corners. The frame-net interface 13 is further perforated witha couple of frame-net fixing holes 14, through which fasteners extend.

The frame-arm fixing section 15 is each positioned on the right and leftside of the rear of the frame 1, declining slightly inwardly toward thelower center of the frame 1. Through the frame-arm fixing device 15 oneach of the left and right side of the frame 1, the supporting arms 4 isassembled to the frame 1. Each of the frame-arm fixing section 15includes a frame-pole fixing groove 151 for engaging with each of thetwo supporting poles; the frame-pole fixing groove 151 is formed withframe-pole fixing bores 152 for locking the supporting pole 41 with theframe-arm fixing device 15, and hence the frame 1.

The latticed net is made from soft materials with its border contactingthe frame-net interface 13 secured by a net fixing loop 5.Alternatively, the net fixing loop 5 can be replaced by any equivalentdevice for nailing the net 2 onto the frame 1.

The frame cover 3 is configured in a loop for mounting onto the frame 1,with both the border of the lattice net 2 and the net fixing loop 5enclosed under the inner side thereof. Furthermore, a suppressing lock31 juts out along the inner surface of the frame cover 3 to suppress inposition both the border of the net 2 and the net fixing loop 5. Framecover fixing bores 32 are configured on the frame cover 3 at locationscorresponding to where the frame-net fixing holes 14 of the frame 1 areformed.

Supporting arms 4 comprises two supporting poles 41, an arm base plate42, and frame-arm fixing pieces 43. The pair of supporting poles 41 ismade of metal, shaped like a curved-V. The metal arm base plate 42 atthe lower ends of the supporting poles 41 connects to a chair seat (notshown in the figures). On the upper portion of the supporting poles 41are formed frame-arm fixing bores 411. The frame-arm fixing piece 43defines a pole-fixing grooves 431 and are formed with pole fixing holes432 in it for engaging supporting arms 4 to the frame 1.

Referring to FIG. 3, in assembly, a latticed net 2 first mounts over theframe-net interface 13 of the frame 1, secured to the frame 1 by afixing loop 5. Since a net 2 is supported by a projecting loop-likefront edge 12, it is empowered with quite durable elasticity. Likewise,by having a sharp angle inside the frame-net interface 13, the netfixing loop 5 functions as a even stronger fastener in engaging the net2 to the frame-net interface 13.

Referring to FIG. 1 to FIG. 6, a frame cover 3 mounts on top of theframe 1, covering the frame-net interface 3 completely. Fasteners (suchas screws) extends through the frame-net fixing holes 14 of the frame 1,and the cover fixing holes 14 of the cover 3 such that the cover 3encompasses the border of the net 2 and the fixing loop 5 underneath. Onthe whole, the backrest after complete assembly gives a single-pieceelegant look. Furthermore, a suppressing loop 31 of a frame cover 3provides an extra force to stabilize the net 2 and the fixing loop 5,and thereby to better secure them onto the frame-net interface 13.

Referring to FIG. 2 and FIG. 5, the upper ends of the pair of supportingpoles 41 of supporting arms 4 are each assembled inside the frame-polefixing groove 151. By having a fastener (such as a screw) extend throughthe pole fixing holes 432 of the frame-arm fixing piece 43, theframe-arm fixing bores 411 of the supporting poles 41, and theframe-pole fixing bore 152 of the frame 1, the frame 1 is armored by thesupporting arms 4 against deformation or rupture (due to heavy weightsor temperature changes), which in turns upholds the elastic tension ofthe net 2.

Although a preferred embodiment in accordance with the present inventionhas been provided in this application, it is to be understood that manyother possible modifications and variations can be made withoutdeparting from the scope of the present invention hereafter claimed.

1. A chair backrest comprising: a frame made of hard plastics shaped like a closed loop with frame fixing holes, wherein the outer front loop-like edge of said frame protrudes outwards facing a chair occupant's back, defining a loop-like frame-net interface with a sharp angle, wherein said frame-net interface being confined by said front loop-like edge and the opposing rear periphery of said frame; said frame-net interface is formed with frame-net fixing holes; on each the right and left side of the rear of said frame is formed a frame-arms fixing section, defining an inner groove and frame-arms connection holes for engagement; a net fixing piece; a net made from soft materials with the border of said net secured onto said frame-net interface by said net fixing piece; a frame cover shaped like a closed loop for mounting over said frame-net interface; said frame cover is configured with cover-fixing bores at locations corresponding to said frame-net fixing holes; along the inner surface of said frame cover is formed a loop-like suppressing lock for stabilizing in position the border of said net and said net fixing piece underneath; and a supporting-arms assembly with branching V-like supporting poles; the upper portion of each said supporting poles connects to said frame-arms fixing section of said frame.
 2. The chair backrest as claimed in claim 1 wherein said net fixing piece is a nailing loop.
 3. The chair backrest as claimed in claim 1 wherein said supporting-arms assembly comprises: two supporting poles, shaped in a V-like branch from bottom to top, with frame-arm fixing bores at the upper portion of said supporting poles; a base plate to which the bottom ends of said two poles connect; and frame-arm fixing pieces for engaging the upper portion of each said supporting pole to said frame-arms fixing section of said frame; each said frame-arms fixing piece defines an inner pole-fixing groove and a pole-fixing bore for fasteners to go through.
 4. The chair backrest as claimed in claim 1 wherein said frame is made from hard plastics, while said supporting poles and said base plate are made of metals.
 5. The chair backrest as claimed in claim 1 wherein said frame is reinforced with a frame supporting board, traversing between the right and left side of said frame in a curve way toward the rear of said frame. 